Hydraulic retractor control



June 26, 1945. IW M FCHL A 2,379,180

HYDRAULI C RETRCTOR CONTROL Filed Feb. lO, 1940 2 Sheets-Sheet lINVENTQR. afffef M ,F/72

June 26, 1945. w.- M PoHL HYDRAULIC RETRAGTOR CONTROL Filed Feb. l0,1940 2 Sheets-511861'I 2 Q5 Nw. www

WN EN WM Y cylinder I and a piston II.

Patented June 26, 1945 HYDRAULIC RETRACTOR CONTROL Walter M. Pohl,Washington, D. C., assigner to Vickers, Incorporated, Detroit, Mich., acorporation of Michigan Application February 1o, 1940, serial No.318,255 'A (c1. so-52) is claims.

This invention relates to a hydraulic retractor control and hasparticularly to do with an improved control system for a hydraulicmotor.

An object of the present invention is t0 prvvide a hydraulic controlsystem in which a novel arrangement oi' valves permits the continuedmovement of a motor to be effected'by slight movement of the motor by anexternal force in the particular direction concerned.

'A further object of the invention is the provision of a system whichmay operate automatically but may be fully controlled by manual op..eration. The hydraulic control system concerned herewith is especiallyadapted tothe rammer mechanism of large guns in which it is desirable tohave the retraction movement initiated by g'un recoil. I t is alsoadapted to a wide variety of commercial apparatus such as conveyingmachinery and the closing and opening of doors on industrial furnaces.

Other objects and features of ,the invention relating to the details ofthe hydraulic circuit and the operation thereof will be brought out inthe following description and claims.

In the drawings: l

Fig. 1 is a circuit diagram mostly in section with each of the conduitsbeing shown in a single plane for purposes of illustration.

Figs. 2 and 3 are views of portions of Fig. 1

showing the parts in diierent relative positions though a portion ofFig. 2 is modied from Fig. 1. An illustration of .the principles oftherinvention will now be described in connection with the drawings. Amotor to be driven, consists of a A rod I2 extends from the motorthrough one end of the cylinder. A motor I3 drives a pump I4 whichserves as a main pressure source and a pump I5 serves as a sourceofipilot pressure. A valve block is shown Vat I5 and in this valve blockare located a directional control valve I'I for controlling pressurefrom the main source.Y A directional control valve i8 controls pressurefrom the pilot source and an additional control valve I9 controls,simultaneously, pressure from said each end thereof and these ports areconnected respectively to conduits 24 and 25 leading from the valve I`It will be seen that the ports 22 and 423 do not enter the cylinder atthe extreme ends tliereof. Additional passageways 26 and 21 lead to apoint directly adjacent the ends of the cylinder and these passagewaysare each closed by a check valve 23.

The valve I'I consists of a spool which is located in a cylindricalrecess inthe housing -I6, said spool having two end piston formations 29and 30 and two central pistons 3| and 32. The lower end of the valve I1extends into a chamber 33 and is surrounded by a spring 34 whichbearsagainst washers 35 and 33. Movement of these washers on the valve islimited in one direction respectively by the piston formation 29 on theone end and a collar 31 at the lower end. The washers have a loose fiton the valve so that pressure may pass around them. as in the Acase of lwasher 38, to the chamber directly below the valve. Whenthe valve is inneutral position, as shown in Fig. l, each of these washers bears on ashoulder in the valve housing and it will thus be seen that the spring34 tends to maintain the valve I1 in its neutral position. Above thepiston formation 30 is formed a chamber 33 and an auxiliary chamber 39is provided above the chamber 38, a piston member 40 extending from thechamber 39 through the chamber 33 to contact the valve. A conduit 4Iconnects the chamber 33 with the valve recess o1' valve I3 andsimilar1y, a conduit 42 connects chamber 3B with valve I3.

The chamber 33 is connected to a valve recess I9a of the valve I 9 by aconduit 43 and this valve recess I9a is also-connected to -an extension2Ia of conduit 2l leading from the pilot pump. A tank conduit 44connects the valve recess of valve II to the tank and a, conduit 45connects valve recess I 9a and valve I8 to the tank.

The valve Iiiv is provided with tank passages 45 and 41, which eachconnect with the conduit 45. 'Ihe ends of this valve are vented to thisline. A spring 43 acts on the valve I3 so that movement of the valvemust be against this spring.

Referring now to the connection between -the valve I8 and the motorIII-I I, the piston rod I2 which moves in and out o'f the cylinder I0 isprovided with a contact member which is adapted to cooperate with. a camlever 5I mounted on a rod 52. At the other end of the rod 52 is a latch53 which connects to a rod 54 at the lower end' of the valve I3. Aspring pressed bell crank 55 pivoted at 53 is provided with a knob 51which 'f is hunted bya relief valve 50 and the pressure in.

conduit 2| is limited by an actuator relief valve 6I which consists of aspring backed piston 62 which bypasses the line 2l to a tank conduit 63when a certain amount of pilot pressure has ac'- cumulated in a chamber84.

A check valve is shown at 61 normally held in closed position by aspring 68. Conduit 69 leads from valve recess of valve I1 to valve 61.The other side of valve 61 is connected with tank conduit 44.

In the operation `oi? the device, assuming that the -piston II was inits extreme right position in cylinder I 0, a movement of lever 59 tothe forward position indicated will shift the latch 53 downward so thatit will be caught beneath the knob 51 on bell crank 55 as shown in Fig.3. Valve I8 will then be shifted to the position shown in Fig. 3 andpilot pressure may pass from conduit 2I to conduit 4I and chamber 33.This will cause an upward shifting of valve I1 and by reason of thisshifting, conduit 20 from the main pressure source will be connected toconduit 25 leading to the right end of cylinder II) (Fig. 3). At thesame time conduit 24 will be connected to tank conduit 44 and piston IIwill start moving in a direction shown by the arrow in Fig. 3.

As the piston II reaches its extreme left position, as shown in Fig. l,the contact member 5,0 will move cam 5| and valve I8 to the positionshown in Fig. 1. This movement of the valve I8 will block pilot pressurefrom conduit 4I and connect both conduits 4I and 42 to the tank conduits45, 46 and 41. Spring 34 maythen return the valve I'I to its neutralposition as shown in Fig. 1. In this position, it will be seen thatpressure from the main conduit 20 maypass around valve I1 to tankconduit 44 and the pump I4 will thus be unloaded. At this time theconduit 24 is also connected to the tank conduit 44 and the conduit 25,leading from the motor, is connected to a short conduit 65 which leadsto the piston end of valve I9. A spring 66 normally maintains the pistonvalve I9 in the position shown so that the conduit 65 is closed fromconduit 20 which passes around the valve I9.

With the parts as shown in Fig. l, it will be seen that a slightmovement of the piston II to the right by an external force will directliquid from cylinder I0 through the conduit 25 to the conduit 65.

Since there is no other outlet for this liquid the piston valve I! willbe shifted to the right thus opening conduit 20 to conduit 25. At thesame time the pilot extension conduit 2 Ia is connected through a recessin piston valve I9 to conduit 43 which leads to the auxiliary chamber 39above piston I1. Pilot pressure will thus be exerted on the pistonmember 40 and the valve I1 will be shifted to the position shown in Fig.2. In this position conduit 24 is blocked from the tank and connected toconduit 20 so that both of the motor ports are connected to the mainpressure source. Because of the differential areas on the respectivesides of the piston II, there will be a continued movement of the pistonto thc right, as shown by the arrow. Consequently, it will be seenthatran automatic retracting movement is eiected by a slight movement inthe same direction exterted on the piston rod I2. In the case of theapplication of the system to the rammel' of a gun, the recoil movementof the gun may be used to effect the slight initiating movement and thehydraulic system will effect the continuation of the movement.

Check valve B1 operates only during the initial movement of theretraction cycle (Fig. 2) to admit uid from the tank to conduit 24 forfilling the void created by the initial movement of piston II beforevalve I1 has been shifted in the manner just explained. It will be seenalso that in case it is so desired, the retraction movement may beinitiated by shifting the hand lever 59 to the retraction positionthereby shifting valve I8 to the position shown in Fig. 2 and connectingconduit 2| with conduit 42 and chanber 38. Also, if immediate retractionis desired the contact member 50 may-be lengthened, as shown in Fig. 2,at 50a so that the cam lever 5I will be shifted, not to its neutralposition, shown in Fig. 1, but to the retraction position, as shown inFig. 2.

What I claim is:

1. In a hydraulic system, a pressure source, a reversible motor means tobe actuated by pressure from said source, means for directing pressureto said motor means to cause actuation in one direction, and meansresponsive to slight movement of said motor in the other direction toeiect continued operation in said other direction of said motor bypressure from 'said source.

2. In a hydraulic system, a pressure source, a reversible motor means tobe actuated by pressure from said source, a pilot operated directionalcontrol valve for directing pressure from said source to said motor tocontrol the movement thereof, a source of pilot pressure, means fordirecting said pilot pressure to said pilot oper- -ated' valve to shiftthe same to cause actuation of said motor in one direction, andadditional means responsive to slight movement of said motor in theother direction to direct pilot pressure to said pilot operated valve tocause continued movement of said motor in said ,other direction.

3. In a hydraulic system, a pressure source, a reversible motor means tobe actuated' by said source comprising a piston-cylinder motor, saidpiston having a greater working area on one side than on the other,means for directing pressure from said source to one side of said pistonto effect movement in one direction, and means responsive to slightmovement of said piston in the other direction to effect continuedoperation in said other direction of said piston by effecting theconnection of both sides thereof to pressure from said source.

4. In a hydraulic system, a main pressure source, a reversible motormeans to be actuated by pressure from said source and having motorports, a pilot operated directional control valve for directing pressurefrom said source having a neutral position in which pressure from saidsource is bypassed and working positions in which pressure is directedto respective ports of said motor to actuate said motor in oppositedirections, a pilot pressure chamber at each end of said control valve,a source of pilot pressure, a pilot valve arranged to be shifted todirect pilot pressure to one or the other of said chambers to shift saidcontrol valve, means for shifting said pilot valve, and additional valvemeans shiftable in response to movement of saidv motor in one directionto effect connection through said control valve of both of said motorports t0 said main pressure source.

5. In a hydraulic system, a main pressure source, a reversible motormeans to be actuated by pressure from said source and having motorports, a pilot operated directional control valve for directing pressurefrom said source having a neutral position in which pressure from saidsource is bypassed and working positions in which pressure is directedto respectiveI ports of said motor to actuate said motory in-oppositedirections, a pilot pressure chamber at each end of said control valve,a source `of pilot pressure, a pilot valve arranged to be shifted todirect pilot pressure to 6. In a hydraulic system, a main pressuresource, a reversible motor means to be actuated by pressure from saidsource and having motor ports, a pilot operated directional controlvalve for directing 'pressure from said source having a neutral positionin which pressure from said source is bypassedl and working positions inwhich pressure is directed to respective ports of said motor to actuatesaid motor in opposite directions. a pilot pressure chamber at each endof said control valve, a source of pilot pressure, a pilot valvearranged to be shifted to direct pilot pressure to said motor, pressurechambers at each end of l said valve for receiving pilot pressure tocause shifting of said valve, an auxiliary chamber at one end of saidvalve, means in said auxiliary chamber responsive to pilotpressuretherein to cause shifting of said valve, pilotI control valvemeans arranged to direct pressure from said pilot source to one of saidpressure chambers to shift said main valve to a working position tocause movement of said motor in one direction, and additional valvemeans for directing pressure from said pilot source to said auxiliarychamber to cause shifting of said Vmain valve, said additional valve.means being responsive to slight movement of said motor in the otherdirection to eifect shifting of said main valve to cause a continuedmovement of said motor in said other direction. Y

9. In a hydraulic system, a main pressure source, a source of pilotpressure, a reversible motor to be shifted by pressure from said mainsource, a main valve for controlling pressure from said source arrangedto be shifted from a neutral one or the other of said chambers to shiftsaid control valve, means for shifting said pilot valve, and additionalvalve means arranged to cooperate with said control valve and sliiftablein response to slight movement 'of said motor in `one direction todirect pilot pressure toshift said confor directing pressure from saidsource having a neutral position in which pressure from said sourceisobypassed and working positions in which pressure is directed torespective ports of said motor to actuate said motor in oppositedirections, a pilot pressure chamber at each end of Y said controlvalve, a source of pilot pressure, a pilot valve arranged to be shiftedto direct pilot 'pressure to one or the`other of said chambersto shiftsaid control valve, means for shifting said pilot valve to cause.setting of said control valve to effect movement of said motor in onedirection,` means operably connected to said pilot valve arranged toshift said pilot valve to neutral position upon 'predetermined movementof said motor in said one direction, and ladditional valve meansarranged to cooperate with said control valve and shiftable, when saidcontrol valve is in neutral position, inresponse to slight movement of-said motor in the other direction to direct pilotI pressure to shiftsaid control valve to a working position wherebypressure from said mainsource will be directed to ,said motor to eect continued operation' insaid other direction.

8. In a hydraulic system, a main pressure source, a source of pilotpressure, a reversible motor to be shifted by pressure from said mainsource, a main valve .for controlling pressure from said source arrangedto be shifted from a neutral position-b said mainsource, to workingpositions in which pressure is directed to position bypassing saidV mainsource, to working positions in which pressure isdirected to said motor,pressure chambers at each `end of said valve for receiving pilotpressure to cause shifting of said valve, an auxiliary chamber at oneend of said valve, means in said auxiliary chamber responsive to pilotpressure therein to cause shifting of said valve, pilot control valvemeans arranged to direct pressure from said pilot source to one of saidpressure chambers to shift said main valve to a worng position to causemovement of said motor in one direction, and additionalV valve means fordirecting pressure from said pilot source to said auxiliary chamber tocause shifting of said main valve, said additional valve means beingresponsive to slight movement of said motor inthe other direction, whensaid main valve is in neutrall position,.toeil'ect transfer of pilotpressure to said auxiliary chamber whereby said main valve is shifted toa working position to cause continued movement of said motor in saidother direction.

, 10. In a hydraulic system, a main pressure source, a soin-ce of pilotpressure, a reversible motor to be shifted by pressure from said mainsource, a main valve for controlling pressure from said source arrangedto be shifted from a -neutral position b said main source, to workingpositions in which pressure is directed to said motor, a means forbiasing said valve to its neutrai position, pressure chambersat each endof said valve for. receiving pilot pressure to cause shifting of saidvalve, an auxiliary `chamber at one end of said valve, means in saidauxiliary chamber to pilot pressure therein to' cause shifting of saidvalve, pilot control valve meansarrangedtodirectpressurefromsaidpilot .Y

source to one of said pressure chambers to shift sammain valve to' aworking position m cause movement of said motor in one direction, and

'additional valve means for. pressure from said pilot source to saidauxiliary chamber to cause shifting of said main valve, said additionalvalve means being e to slight movement of said motor in the otherdirection to effect shifting of said m'ain valve tocause a continuedmovement of said motor in said 'other direction.

rl1. In va hydraulic system, amain pressure source, asource of pilotpressure, a reversible motor to be shifted bypressure from said mainsource,a main valve for controlling pressure from sure from sai saidsource arranged to be shifted from a neutral position bypassing saidmain source, to working positions in which pressure is directed to saidmotor, pressure chambers at each endl of said valve for receiving pilotpressure to cause shifting of said valve, an auxiliary chamber at oneend of said valve, means in said auxiliary chamber responsive topilotpressure therein to cause shifting of said valve, pilot controlvalve means arranged to direct pressure from said pilot source to one ofsaid pressure chambers to shift said main valve to a Working position tocause movement of said motor in one direction, means, for causingautomatic shifting of said main valve to neutral position in response toa predetermined movement of said motor, and additional valve means fordirecting pressure from said pilot source to said auxiliary chamber tocause shifting of said main valve, said additional valve means beingresponsive to slight movement of said motor in the other direction, whensaid main valve is in neutral position, to eiect transfer of pilotpressure to said auxiliary chamber whereby said main valve is shifted toa working position to 'cause continued movement of said motor in saidother direction.

12. In a hydraulic system, a pressure source, a reversible motor meansto be actuated by pressource, motor ports on said motor and conduitmeans for connecting said ports to said pressure source, valve means insaid conduit means shiftable to control the iiow of pressure from saidsource to said ports and thereby control the direction and movement ofsaid motor, a source of pilot pressure, and pilot control means adaptedto control the inuence of pilot pressure on said first named valvemeans, said pilot control means comprising a manually operated valve andan auxiliary control valve adapted to be pressure operated, saidmanually operated valve being adapted to control the ow of pilotpressure to and consequent shifting of said first named valve means ineither direction, said auxiliary valve means being responsive to slightmovement oi said motor in one direction to direct pressure to said rstnamed valve means to shift the same and cause continued operation ofsaid 4motor in said direction by pressure from said source.

13. In a hydraulic system, a pressure source, a motor means comprisingrelatively movable parts to be actuated by pressure from said source,valve means shiftable to operatingpositions for directing pressure tosaid motor means to cause actuation thereof, and means hydraulicallyshiftable in response to pressure built up by relative movement of saidmotor parts by an external force and cooperating to cause shifting ofsaid yvalve means to an operating position to effect continued relativemovement of said partsby pressure from said source in the same directionas that initiated by the external force.

WALTER M. POHL.

